Engine starter gearing



c. A. MENDENHALL 2,900,827

ENGINE STARTER GEARING Filed Dec. 31, 1957 I u 1 6 1 m a .H. m a xQw/n m m 3 w w a m r z w Q A 3 4: J. 5 6 z m 6 a M 1 Aug. 25, 1959 168a. INVENTOR.

A TORNEY WITNESS:

United States Patent ENGINE STARTER GEARIN G Charles A. Mendenhall, Horseheads, N.Y., assignor to Bendix Aviation Corporation, Elmira Heights, N.Y., a corporation of Delaware Application December 31, 1957, Serial No. 706,364

7 Claims. (Cl. 747) It is another object to provide such a device in which the mass of the parts which overrun when the engine starts is very small, whereby overrunning takes place freely and quietly.

It is another object to provide such a device in which the polar moment of inertia of substantially the entire mass of the drive is effective to insure traversal of the pinion into mesh with the engine gear.

It is another object to provide such a device embodying centrifugal means for ensuring traversal of the drive back to idle position when the engine has been started.

Further objects and advantages will be apparent from the following description taken in connection with the ac companying drawing in which:

Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention showing the parts in normal or idle position;

Fig. 2 is a similar view showing the part in cranking position;

Fig. 3 is a detail of the driving and traversing member; and

Fig. 4 is a section taken substantially on the line 4-4 of Fig. 1.

In Fig. 1 of the drawing there is shown a power shaft 1 which may be the extended armature shaft of a starting motor not illustrated, on which a driving and traversing member 2, best shown in Fig. 3, is slidably journalled. The driving member 2 is provided with spiral slots or channels 3, 4; and a pin 5 having a press fit in the shaft 1 has its ends extending into said channels to form a traversing and driving connection from the power shaft to the driving member.

A barrel member 6 is mounted at one end on the driving member 2, and is provided with axially extending slots 7 receiving lugs 8 extending radially from the driving member and retained in the barrel by a lock ring 9. A pinion 11 is slidably journalled on the power shaft 1 for movement into and out of engagement with an engine gear 12, and has a driven overrunning clutch member 13 fixed thereon in any suitable manner and retained in the open end of the barrel 6 by a lock ring 14.

A driving coupling member 15, hearing slidably on the power shaft 1 is provided with radial lugs 16 slidably traversing longitudinal slots 17 in the barrel 6 to thereby form a splined connection from the barrel to said driving coupling member. The driving coupling member 15 has inclined torque-transmitting projections 18 engaging similar projections 19 on an intermediate coupling member 21 which also bears slidably on the power shaft 1 and has ice overrunning clutch teeth 23 engaging similar teeth 24 on the driven overrunning clutch member 13.

Yielding means for resisting separation of the coupling members 15, 21 is provided comprising a ring 25 of elastically deformable material such as rubber, bearing at one side on the driving coupling member 15 and at the other side on a spring thrust washer 26 located in the barrel and normally bearing against the pin 5, thus defining the idle position of the drive. A spring 27 between the driving coupling member 15 and the intermediate coupling member 21 normally maintains the overrunning clutch teeth 23, 24 in engagement.

A yielding detent member 28 is mounted for radial sliding movement in the barrel 6 and has a head 29 positioned to engage the pin 5 when the parts are in idle position as illustrated in Fig. 1, the detent being yieldably pressed inward by suitable means such as an elastic ring 31 whereby the detent yieldingly resists movement of the drive away from idle position. During the meshing movement the detent 28 passes over the end of the pin 5 and drops down on the other side of the pin as shown in Fig. 2, in which position it cooperates with the pin to resist demeshing movement of the drive assembly.

Centrifugal means are provided for frictionally connecting the pinion 11 to the barrel 6 when the pinion overruns, in order to ensure traversal of the drive as sembly back to idle position when the engine starts. As best shown in Fig. 4, this means comprises a split spring drag member 32 which is mounted in a seat 33 on the periphery of the driven clutch member 13, and connected thereto at one end as by means of a loop 34 entering a recess 35 in said clutch member. The loop 34 is preferably formed at the forward end of the member 32 as respects its direction of rotation, so that said. drag member is drawn rather than being pushed by said loop.

In operation, starting with the parts as. illustrated in Fig. 1, rotation of the power shaft 1 by the starting motor, not illustrated, in the direction of the arrow causes the pin 5 to advance the driving member 2 together with its associated parts to the right, by virtue of its engagement in the spiral slots 3, 4. This movement is resisted yieldingly by the detent 28, but the detent spring 31 is so selected as to permit this movement to takeplace without undue reluctance. The traversal continues until the pinion 11 is fully meshed with the engine gear 12, at which time the meshing movement is arrested by engage ment of the pin 5 against the shoulder 36 formed on the driving member 2 at the ends of the slots 3, 4.

Further rotation of the power shaft 1 causes torque to be transmitted from the driving member 2 to the barrel 6 and thus to the driving coupling member 15. This torque is transmitted through the inclined connection 18, 19 to the intermediate coupling member 21 which thereupon rotates the pinion 11 through overrunning clutch teeth 23, 24.

Due to the inclined connection 18, 19 the driving coupling member 15 is wedged away from the intermediate coupling member 21 against the compression of the rubber ring 25 as confined by the spring thrust washer 26. If the initial shock load placed on the drive due to the deceleration torque of the starting motor reaches a predetermined value, the elastic ring 25 permits the projections 18 to slide past the projections 19 until the excess torque is dissipated, after which the cranking torque is transmitted without further slippage.

When the engine starts, the acceleration of the engine gear 12 causes the pinion 11 to overrun the barrel 6 as permitted by the overrunning clutch connection 23, 24. At this time traversal of the drive back to idle position is yieldably resisted by the detent 28 as illustrated in Fig. 2.

When the speed of the pinion 11 reaches a predetermined value indicative of the fact that the engine is now reliably self-operative, the drag ring 32 is expanded by centrifugal force into engagement with the interior of the barrel 6 with sufficient pressure to accelerate the barrel with respect to the power shaft 1, overcoming the detent 28 and causing the parts to be returned to idle position. The pressure of the detent 23 is at the critical time reduced by centrifugal force so as to facilitate this traversal.

The backward movement of the drive assembly is arrested and cushioned by engagement of the spring thrust washer 26 against the pin 5, and thereafter the parts are retained in idle position by the detent 28 until the next actuation of the starting motor.

Although but one form of the invention has been shown and described in detail it will be understood that other forms are possible and changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a driving and traversing member having a spiral slot formed therein slidably journalled on said shaft, a pin fixedly mounted in the shaft and projecting radially therefrom slidably engaging said spiral slot, a barrel member surrounding the driving member and rigidly mounted at one end thereon, a pinion rotatably retained in the other end of the barrel and slidably journalled on the power shaft for movement into and out of mesh with a gear of an engine to be started, and means in the barrel for rotating and traversing the pinion comprising a driving coupling member connected to rotate with the barrel with freedom for limited relative longitudinal movement, an intermediate coupling member having an inclined driving connection with the driving coupling member and an overrunning clutch connection with the pinion, yielding means in the barrel normally holding the driving coupling member at the limit of its movement toward the intennediate coupling member but permitting the intermediate coupling member to declutch itself from the pinion, and spring means normally holding the intermediate coupling member and the pinion advanced in the barrel member toward the engine gear.

2. An engine starter drive as set forth in claim 1 in which the means for resisting separation of the coupling members comprises an elastically compressible member arranged to permit the coupling members to wedge apart and allow relative rotation thereof responsive to a predetermined overload on the drive.

3. An engine starter drive as set forth in claim 1 including further an annular thrust member anchored in the barrel adjacent the inner end of the driving and traversing member, and normally engaging said pin to define the idle position of the drive.

4. An engine starter drive as set forth in claim 1 in cluding further a yielding detent mounted for limited radial movement in the barrel in position to engage the projecting end of said pin and cooperate therewith to resist movement of the drive away from idle position and away from cranking position.

5. An engine starter drive as set forth in claim 3 in which the means for resisting separation of the coupling members comprises a ring of elastically deformable material in the barrel bearing against the driving coupling member, and said thrust member is in the form of an elastic washer compressing said ring and cooperating with said pin to cushion the demeshing movement of the drive and define its idle position.

6. An engine starter drive as set forth in claim 4 including further centrifugally actuated means for frictionally coupling the pinion to the barrel.

7. An engine starter drive as set forth in claim 6 in which said coupling means includes a split ring member anchored to the pinion and movable by centrifugal force into frictional contact with the interior of the barrel.

References Cited in the file of this patent UNITED STATES PATENTS 2,469,854 Ulrich et al May 10, 1949 

